1. Field of the Invention
The present invention relates to a method for manufacturing a microcrystalline semiconductor film, a method for manufacturing a thin film transistor having the microcrystalline semiconductor film, and a method for manufacturing a photoelectric conversion device having at least one pair of semiconductor junctions in the microcrystalline semiconductor film.
2. Description of the Related Art
In recent years, technology for forming thin film transistors using a thin semiconductor film (with a thickness of from several tens of nanometers to several hundred nanometers, approximately) formed over a substrate having an insulating surface has been attracting attention. Thin film transistors are applied to a wide range of electronic devices such as ICs or electro-optical devices, and prompt development of thin film transistors that are to be used as switching elements in image display devices, in particular, is being pushed.
As a switching element in an image display device, a thin film transistor including an amorphous semiconductor film, a thin film transistor including a polycrystalline semiconductor film having a crystal grain of 100 nm or more, or the like is used. As a method for forming a polycrystalline semiconductor film, a technique is known in which a pulsed excimer laser beam is processed into a linear shape with an optical system, and an amorphous silicon film is scanned and irradiated with the linear beam to be crystallized.
In addition, as a switching element in an image display device, a thin film transistor using a microcrystalline semiconductor film is used (Reference 1: Japanese Published Patent Application No. H4-242724 and Reference 2: Japanese Published Patent Application No. 2005-49832).
Further, development of a photoelectric conversion device has been proceeding, in which microcrystalline silicon as crystal-system silicon capable of being manufactured by a plasma CVD method is used as a photoelectric conversion layer (e.g., see Reference 3: Japanese Published Patent Application No. 2000-277439).